Yeah, that is a problem. God damn it and you asked for lower spread, now look what happens! No one loves Heavy no more!
Hey I said it needed a small buff in spread, not simultaneous overboard buff to it along with a further increase in fire rate. Your problem here lies in the fact that now that it has too short of a range, you will hardly be able to make 2 ammo types effective on it, in earlier updates the advantages of Heavy vs Greased very too obvious (due to 700 meter range), now.. not so much, not much you can do about it, you either make it innaccurate enough so Greased can be used only at face hugging range, making everyone choose Heavy over it, or you make it accurate enough so Greased is the only option.
Aka, Raycast weapons are annoying to balance.
Light carronades don't even oneclip bloons on closest distance with charged anymore.
I can imagine that the Heavy Carronade is even worse then, since a Light Carronade does more damage than a full clip of the Heavy Carronade in one go. Wait, how is this possible? You sure you can't one-clip it if all projectiles land?